Biden and Booker were both thrown off by protesters early in the debate. Biden kept mixing up the cost of Medicare-for-all (was it $3 trillion over 10 years, or $30 trillion?). Biden, Harris and Sen. Michael F. Bennet (D-Colo.) kept stumbling over their words, with Biden at one point referring to Booker as “the future president.” Sen. Kirsten Gillibrand (D-N.Y.) at one point had nothing ready to go when she was brought in on a discussion, emitting a painful “um” that drew laughter. And even in Harris’s opening statement, while hailing her ability to prosecute the case against Trump, the senator messed up her talking point, saying she would “prosecute the case of four more years of Donald Trump . . . and against him.” WP